In packaging a product in cases, the product to be packaged typically must be conveyed from a first position where the product is collated into an array suitable for being placed in a case of a predetermined size to a second position where the product is typically moved sidewise into the case or the product is lowered or dropped from a position above the case into the case. The case is then sealed with the enclosed product and the case and product are then ready for transportation to a distribution centre.
If a product can be dropped into a case without damaging the product or the container, this method is satisfactory. Many products, however, cannot be dropped without the possibility of damage to the product or to the container holding the product. In using the sidewise loading method, one technique is to simply seal the case after moving the product into the case. This method, however, results in the flaps of the case being on the side of the case when the product is properly oriented which is unsatisfactory for the retailer. A second technique using side loading is to load the product into the case, seal the case and then rotate it such that the flaps are in the normally closed position on both the bottom and top of the case. Again, however, this results in rotating the product which, in some cases, may be unacceptable.
Where the product must be treated gently and minimal product movement is desired, a favoured technique is case-over packaging where the case is lowered over the product and the flaps are sealed. In this method, the product is subject to a minimum of movement, it retains its "right-side-up" orientation and the case has its closed flaps on the bottom and the top as is normal.
Existing case-over type machines, however, have problems when the product is moved relative to the case and, similarly, when the case is lowered over the product. When the product has a regular shape such as cereal boxes and the like, the consistency of positioning the case over the product without mishap is usually high. This is so since the rows and tiers of the array allow the product to be transported between the loading and packaging positions without any irregular and unexpected forces occurring which would tend to separate the various product boxes and destroy the array. This is similarly true when the case is moved to surround the product in the packaging position.
However, when the product is of an irregular shape such as when the product is, for example, cookie bags, the array is unstable with the result that it may collapse when it is being transported or when the case is lowered over the product in final packaging. The dislocation caused by the array collapse or displacement of the product during packaging can cause the packaging line to shut down or, at least, to be slowed. This is clearly unsatisfactory.
A system such as the system illustrated and described in U.S. Pat. No. 3,762,129 to Salomon discloses a constraint system which utilizes two stationary guide walls to constrain an irregularly shaped product in the form of tea bags from the product loading position to the case over packaging position. In addition, Salomon utilizes two sets of spacer fingers which move with the product and which constrain it until the case has been lowered over the product.
While the Salomon system is clearly an advance, it too remains unsatisfactory in at least one aspect. The guide walls are stationary rather than movable with the product. This causes friction between the product and the guide walls with the result that undesirable and unnecessary forces are created which tend, as mentioned, to cause the product array to collapse.
Yet a further problem with existing case-over packaging relates to the product support walls which support the product when the packaging takes place. When the case is lowered over the product, it is important that the product not protrude which can cause interference with the case when it is being lowered. Nor should the product constraint require small design tolerances which, when the tolerances are exceeded, can cause the case to hit the product constraint when it is lowered. Likewise, it is desirable to allow the product constraint used in previous machines to have some flexibility such that there will be increased tolerance when interference between the case and the product occur so as to allow the packaging operation to continue without product line shutdown or slowdown.
Yet a further disadvantage with existing packaging machines relates to the techniques which are used to close the bottom major and minor flaps of the case after it is lowered over the product. Typically, with either the major or minor flaps open on the product support rails, the case together with the product is conveyed through a plow frame which has a solid leading edge and which is angularly oriented relative to the flaps so that the flaps contact the leading edges which then force the flaps inwardly and close them. The angle of the leading edges of the plow is of considerable importance since if the angle is too shallow, the flaps will not fold under the case but, rather, they will jam against the leading edge of the plow. In order to provide for a leading edge which allows the flaps to be closed in all events, the included angle between the rollers must be relatively narrow which means the case may have to be transported over a relatively large distance before the flaps are entirely closed. This long distance is undesirable since speed is an important consideration in packaging operations.
Yet another disadvantage of existing packaging machines relates to case erectors. Previous case erectors have utilized a pair of grippers for the flaps which were located on adjacent sides of the case. Such a design, while offering good support to the two adjacent sides of the case, did not offer adequate support to the oppositely located sides. Such support is important in order to reduce misalignment of the case while the case is being lowered over the product for reasons discussed. A reduction in the misalignment of the case relative to the product reduces the possibility of interference between the product and the case.
Yet a further disadvantage with packaging machines and, in particular, with the case magazines of such machines, lies in the method and apparatus used to maintain the cases in contact with the separator bar which separates one case from the plurality of cases in the magazine. Previously, a walking beam type arrangement was used which, while it operated satisfactorily to keep the cases in contact with the separator bar, was costly because of numerous and extensive moving parts. The numerous parts also contributed to mechanical breakdown and the necessity for frequent maintenance and service operations.